<?php
/**
 * Smarty plugin
 *
 * @package Smarty
 * @subpackage Security
 * @author Uwe Tews
 */

/*
 * FIXME: Smarty_Security API
 *      - getter and setter instead of public properties would allow cultivating an internal cache properly
 *      - current implementation of isTrustedResourceDir() assumes that Smarty::$template_dir and Smarty::$config_dir are immutable
 *        the cache is killed every time either of the variables change. That means that two distinct Smarty objects with differing
 *        $template_dir or $config_dir should NOT share the same Smarty_Security instance,
 *        as this would lead to (severe) performance penalty! how should this be handled?
 */

/**
 * This class does contain the security settings
 */
class Smarty_Security {

	/**
	 * This determines how Smarty handles "<?php ... ?>" tags in templates.
	 * possible values:
	 * <ul>
	 *   <li>Smarty::PHP_PASSTHRU -> echo PHP tags as they are</li>
	 *   <li>Smarty::PHP_QUOTE    -> escape tags as entities</li>
	 *   <li>Smarty::PHP_REMOVE   -> remove php tags</li>
	 *   <li>Smarty::PHP_ALLOW    -> execute php tags</li>
	 * </ul>
	 *
	 * @var integer
	 */
	public $php_handling = Smarty::PHP_PASSTHRU;
	/**
	 * This is the list of template directories that are considered secure.
	 * $template_dir is in this list implicitly.
	 *
	 * @var array
	 */
	public $secure_dir = array();
	/**
	 * This is an array of directories where trusted php scripts reside.
	 * {@link $security} is disabled during their inclusion/execution.
	 *
	 * @var array
	 */
	public $trusted_dir = array();
	/**
	 * List of regular expressions (PCRE) that include trusted URIs
	 *
	 * @var array
	 */
	public $trusted_uri = array();
	/**
	 * This is an array of trusted static classes.
	 *
	 * If empty access to all static classes is allowed.
	 * If set to 'none' none is allowed.
	 * @var array
	 */
	public $static_classes = array();
	/**
	 * This is an array of trusted PHP functions.
	 *
	 * If empty all functions are allowed.
	 * To disable all PHP functions set $php_functions = null.
	 * @var array
	 */
	public $php_functions = array(
        'isset', 'empty',
        'count', 'sizeof',
        'in_array', 'is_array',
        'time',
        'nl2br',
	);
	/**
	 * This is an array of trusted PHP modifers.
	 *
	 * If empty all modifiers are allowed.
	 * To disable all modifier set $modifiers = null.
	 * @var array
	 */
	public $php_modifiers = array(
        'escape',
        'count'
        );
        /**
         * This is an array of allowed tags.
         *
         * If empty no restriction by allowed_tags.
         * @var array
         */
        public $allowed_tags = array();
        /**
         * This is an array of disabled tags.
         *
         * If empty no restriction by disabled_tags.
         * @var array
         */
        public $disabled_tags = array();
        /**
         * This is an array of allowed modifier plugins.
         *
         * If empty no restriction by allowed_modifiers.
         * @var array
         */
        public $allowed_modifiers = array();
        /**
         * This is an array of disabled modifier plugins.
         *
         * If empty no restriction by disabled_modifiers.
         * @var array
         */
        public $disabled_modifiers = array();
        /**
         * This is an array of trusted streams.
         *
         * If empty all streams are allowed.
         * To disable all streams set $streams = null.
         * @var array
         */
        public $streams = array('file');
        /**
         * + flag if constants can be accessed from template
         * @var boolean
         */
        public $allow_constants = true;
        /**
         * + flag if super globals can be accessed from template
         * @var boolean
         */
        public $allow_super_globals = true;

        /**
         * Cache for $resource_dir lookups
         * @var array
         */
        protected $_resource_dir = null;
        /**
         * Cache for $template_dir lookups
         * @var array
         */
        protected $_template_dir = null;
        /**
         * Cache for $config_dir lookups
         * @var array
         */
        protected $_config_dir = null;
        /**
         * Cache for $secure_dir lookups
         * @var array
         */
        protected $_secure_dir = null;
        /**
         * Cache for $php_resource_dir lookups
         * @var array
         */
        protected $_php_resource_dir = null;
        /**
         * Cache for $trusted_dir lookups
         * @var array
         */
        protected $_trusted_dir = null;


        /**
         * @param Smarty $smarty
         */
        public function __construct($smarty)
        {
        	$this->smarty = $smarty;
        }

        /**
         * Check if PHP function is trusted.
         *
         * @param string $function_name
         * @param object $compiler compiler object
         * @return boolean true if function is trusted
         * @throws SmartyCompilerException if php function is not trusted
         */
        public function isTrustedPhpFunction($function_name, $compiler)
        {
        	if (isset($this->php_functions) && (empty($this->php_functions) || in_array($function_name, $this->php_functions))) {
        		return true;
        	}

        	$compiler->trigger_template_error("PHP function '{$function_name}' not allowed by security setting");
        	return false; // should not, but who knows what happens to the compiler in the future?
        }

        /**
         * Check if static class is trusted.
         *
         * @param string $class_name
         * @param object $compiler compiler object
         * @return boolean true if class is trusted
         * @throws SmartyCompilerException if static class is not trusted
         */
        public function isTrustedStaticClass($class_name, $compiler)
        {
        	if (isset($this->static_classes) && (empty($this->static_classes) || in_array($class_name, $this->static_classes))) {
        		return true;
        	}

        	$compiler->trigger_template_error("access to static class '{$class_name}' not allowed by security setting");
        	return false; // should not, but who knows what happens to the compiler in the future?
        }

        /**
         * Check if PHP modifier is trusted.
         *
         * @param string $modifier_name
         * @param object $compiler compiler object
         * @return boolean true if modifier is trusted
         * @throws SmartyCompilerException if modifier is not trusted
         */
        public function isTrustedPhpModifier($modifier_name, $compiler)
        {
        	if (isset($this->php_modifiers) && (empty($this->php_modifiers) || in_array($modifier_name, $this->php_modifiers))) {
        		return true;
        	}

        	$compiler->trigger_template_error("modifier '{$modifier_name}' not allowed by security setting");
        	return false; // should not, but who knows what happens to the compiler in the future?
        }

        /**
         * Check if tag is trusted.
         *
         * @param string $tag_name
         * @param object $compiler compiler object
         * @return boolean true if tag is trusted
         * @throws SmartyCompilerException if modifier is not trusted
         */
        public function isTrustedTag($tag_name, $compiler)
        {
        	// check for internal always required tags
        	if (in_array($tag_name, array('assign', 'call', 'private_filter', 'private_block_plugin', 'private_function_plugin', 'private_object_block_function',
                    'private_object_function', 'private_registered_function', 'private_registered_block', 'private_special_variable', 'private_print_expression', 'private_modifier'))) {
        	return true;
                    }
                    // check security settings
                    if (empty($this->allowed_tags)) {
                    	if (empty($this->disabled_tags) || !in_array($tag_name, $this->disabled_tags)) {
                    		return true;
                    	} else {
                    		$compiler->trigger_template_error("tag '{$tag_name}' disabled by security setting", $compiler->lex->taglineno);
                    	}
                    } else if (in_array($tag_name, $this->allowed_tags) && !in_array($tag_name, $this->disabled_tags)) {
                    	return true;
                    } else {
                    	$compiler->trigger_template_error("tag '{$tag_name}' not allowed by security setting", $compiler->lex->taglineno);
                    }
                    return false; // should not, but who knows what happens to the compiler in the future?
        }

        /**
         * Check if modifier plugin is trusted.
         *
         * @param string $modifier_name
         * @param object $compiler compiler object
         * @return boolean true if tag is trusted
         * @throws SmartyCompilerException if modifier is not trusted
         */
        public function isTrustedModifier($modifier_name, $compiler)
        {
        	// check for internal always allowed modifier
        	if (in_array($modifier_name, array('default'))) {
        		return true;
        	}
        	// check security settings
        	if (empty($this->allowed_modifiers)) {
        		if (empty($this->disabled_modifiers) || !in_array($modifier_name, $this->disabled_modifiers)) {
        			return true;
        		} else {
        			$compiler->trigger_template_error("modifier '{$modifier_name}' disabled by security setting", $compiler->lex->taglineno);
        		}
        	} else if (in_array($modifier_name, $this->allowed_modifiers) && !in_array($modifier_name, $this->disabled_modifiers)) {
        		return true;
        	} else {
        		$compiler->trigger_template_error("modifier '{$modifier_name}' not allowed by security setting", $compiler->lex->taglineno);
        	}
        	return false; // should not, but who knows what happens to the compiler in the future?
        }

        /**
         * Check if stream is trusted.
         *
         * @param string $stream_name
         * @return boolean true if stream is trusted
         * @throws SmartyException if stream is not trusted
         */
        public function isTrustedStream($stream_name)
        {
        	if (isset($this->streams) && (empty($this->streams) || in_array($stream_name, $this->streams))) {
        		return true;
        	}

        	throw new SmartyException("stream '{$stream_name}' not allowed by security setting");
        }

        /**
         * Check if directory of file resource is trusted.
         *
         * @param string $filepath
         * @return boolean true if directory is trusted
         * @throws SmartyException if directory is not trusted
         */
        public function isTrustedResourceDir($filepath)
        {
        	$_template = false;
        	$_config = false;
        	$_secure = false;

        	$_template_dir = $this->smarty->getTemplateDir();
        	$_config_dir = $this->smarty->getConfigDir();

        	// check if index is outdated
        	if ((!$this->_template_dir || $this->_template_dir !== $_template_dir)
        	|| (!$this->_config_dir || $this->_config_dir !== $_config_dir)
        	|| (!empty($this->secure_dir) && (!$this->_secure_dir || $this->_secure_dir !== $this->secure_dir))
        	) {
        		$this->_resource_dir = array();
        		$_template = true;
        		$_config = true;
        		$_secure = !empty($this->secure_dir);
        	}

        	// rebuild template dir index
        	if ($_template) {
        		$this->_template_dir = $_template_dir;
        		foreach ($_template_dir as $directory) {
        			$directory = realpath($directory);
        			$this->_resource_dir[$directory] = true;
        		}
        	}

        	// rebuild config dir index
        	if ($_config) {
        		$this->_config_dir = $_config_dir;
        		foreach ($_config_dir as $directory) {
        			$directory = realpath($directory);
        			$this->_resource_dir[$directory] = true;
        		}
        	}

        	// rebuild secure dir index
        	if ($_secure) {
        		$this->_secure_dir = $this->secure_dir;
        		foreach ((array) $this->secure_dir as $directory) {
        			$directory = realpath($directory);
        			$this->_resource_dir[$directory] = true;
        		}
        	}

        	$_filepath = realpath($filepath);
        	$directory = dirname($_filepath);
        	$_directory = array();
        	while (true) {
        		// remember the directory to add it to _resource_dir in case we're successful
        		$_directory[$directory] = true;
        		// test if the directory is trusted
        		if (isset($this->_resource_dir[$directory])) {
        			// merge sub directories of current $directory into _resource_dir to speed up subsequent lookups
        			$this->_resource_dir = array_merge($this->_resource_dir, $_directory);
        			return true;
        		}
        		// abort if we've reached root
        		if (($pos = strrpos($directory, DS)) === false || !isset($directory[1])) {
        			break;
        		}
        		// bubble up one level
        		$directory = substr($directory, 0, $pos);
        	}

        	// give up
        	throw new SmartyException("directory '{$_filepath}' not allowed by security setting");
        }

        /**
         * Check if URI (e.g. {fetch} or {html_image}) is trusted
         *
         * To simplify things, isTrustedUri() resolves all input to "{$PROTOCOL}://{$HOSTNAME}".
         * So "http://username:password@hello.world.example.org:8080/some-path?some=query-string"
         * is reduced to "http://hello.world.example.org" prior to applying the patters from {@link $trusted_uri}.
         * @param string $uri
         * @return boolean true if URI is trusted
         * @throws SmartyException if URI is not trusted
         * @uses $trusted_uri for list of patterns to match against $uri
         */
        public function isTrustedUri($uri)
        {
        	$_uri = parse_url($uri);
        	if (!empty($_uri['scheme']) && !empty($_uri['host'])) {
        		$_uri = $_uri['scheme'] . '://' . $_uri['host'];
        		foreach ($this->trusted_uri as $pattern) {
        			if (preg_match($pattern, $_uri)) {
        				return true;
        			}
        		}
        	}

        	throw new SmartyException("URI '{$uri}' not allowed by security setting");
        }

        /**
         * Check if directory of file resource is trusted.
         *
         * @param string $filepath
         * @return boolean true if directory is trusted
         * @throws SmartyException if PHP directory is not trusted
         */
        public function isTrustedPHPDir($filepath)
        {
        	if (empty($this->trusted_dir)) {
        		throw new SmartyException("directory '{$filepath}' not allowed by security setting (no trusted_dir specified)");
        	}

        	// check if index is outdated
        	if (!$this->_trusted_dir || $this->_trusted_dir !== $this->trusted_dir) {
        		$this->_php_resource_dir = array();

        		$this->_trusted_dir = $this->trusted_dir;
        		foreach ((array) $this->trusted_dir as $directory) {
        			$directory = realpath($directory);
        			$this->_php_resource_dir[$directory] = true;
        		}
        	}

        	$_filepath = realpath($filepath);
        	$directory = dirname($_filepath);
        	$_directory = array();
        	while (true) {
        		// remember the directory to add it to _resource_dir in case we're successful
        		$_directory[] = $directory;
        		// test if the directory is trusted
        		if (isset($this->_php_resource_dir[$directory])) {
        			// merge sub directories of current $directory into _resource_dir to speed up subsequent lookups
        			$this->_php_resource_dir = array_merge($this->_php_resource_dir, $_directory);
        			return true;
        		}
        		// abort if we've reached root
        		if (($pos = strrpos($directory, DS)) === false || !isset($directory[2])) {
        			break;
        		}
        		// bubble up one level
        		$directory = substr($directory, 0, $pos);
        	}

        	throw new SmartyException("directory '{$_filepath}' not allowed by security setting");
        }

}

?>